The render engine analysis series: V-Ray

10.10.2017 Home >Blog >The render engine analysis series: V-Ray

In this series, we take you through some of the different render engines that are out there. There are plenty of them, all with their perks and downsides. This series explores Arnold, V-Ray, mental ray, and Redshift – all for Maya 2017. The lighting set up will be the same, and we’ll see if it’s possible to get the same results.
In this scene, our Render Wrangler Iris will use a HDRI for the overall lighting, four lights at the doors to mimic strong light falling through the door openings, and some extra small lights to highlight details or to light up the overall scene

Originating from Chaos Group in Bulgaria, this render engine is based on global illumination algorithms, based on the idea that light does not only come from a single light source, but can also come from light that has bounced of off a (reflective) surface.

So it sounds a bit more simple than the Monte Carlo algorithm but let’s have a look.

For this blog, I’m using V-Ray 3.40.06, with an IBL called a VRayLightDome. Tick “use dome tex” as this will allow you to upload a hdri. Try a render and if it is very dark increase the intensity multiplier. V-Ray does not work with exposure – it works a multiplier, so for every amount you go up the light is multiplied. Pretty darn straightforward, right?

When I hit render, without doing anything to the standard render settings, I immediately notice that the render takes longer than the Arnold render. Oh dear… but I did not give in! I didn’t start to franticly panic about why this happened, hoping for the best. Instead, I continued to add a few lights: 4 lights to be exact, at the doors . I tweaked them a bit, setting the light temperature to 6500 and the multiplier to 20. The renders proved that it just was not enough, and I have been tweaking each individual light to get the result I wanted. One of the lights is at 30 multiplier, the other only at 5 – so let’s have a play.

And now let’s do a render! What do we get . . .

Vray 3D barn render

Not too shabby! I like how most of the shadows react and I am fairly happy with the amount of grain. But of course, it’s not done yet.

As the scene has an overly dark feel, I am going to put an ambient light in the scene. Now, opinions are much divided about ambient light. Some say it flattens your shadows; others say it is an amazing way to lift-up a scene. Like most of us here at YellowDog, I say moderation. I think it is always good to have one in a scene to prevent negative shadows (shadows that are so black they go below the 0 value).

I have added my light in and set the intensity of 0.015. If you just want to prevent negative blacks, set it to 0.001.

As you can see, it makes my shadow a whole lot less intense, so if you are going for that look, an ambient light is not the way to go. Otherwise it is a great little light to get your overall lighting up a bit.

But my image is still a bit too dark, and I want to add some of that light coming from the camera.

I will create a VRaylightRect and place it just behind my camera. Do not place it just in front, as your render will be black. I want to mimic that warmer, softer light that we already have in the image, and not blow it out of proportions with a bright white/blue light. Again, I am setting the temperature to 5000. I am also going to do is to set my Directional to be more narrow than usual.  I will set it to 0.9 and my directional preview length to about 10.

I am getting a lovely light strip that breaks up the shadows a bit, as is happening on the reference image as well. Maybe we can get some more light on the walls as well. I am going to make another rectangular light and point it towards the walls and ceiling. I am pointing my light slightly towards the ceiling, and with Directional and Directional preview length I can make the light not touch the ground and not too much of the walls. I have put the multiplier to 9.0.

I feel like we are getting really close. Now comparing the image to the original, I think I want a bit more bright light coming through the left doors, as that is where the main Lightsource is coming from. I’m going to up the intensity, and I have also cheated a bit by changing the type of material on the door. I have gone from a lambert with no reflection or spec to a blinn. This should make it slightly more reflective, and hopefully get some bounce light.

This result makes me happy. Although I think it is a tad darker from the original image, I think all my lights otherwise are creating a similar look, and I am now going to have a look at my render settings and tweak them a bit. Keep in mind that, like with Arnold, changing the render settings will affect everything in the scene, and might significantly increase the render time.

Let’s work left to right on the tabs:

  • In the Common tab, make sure you have the correct render camera and correct resolution you want to render in selected. As you are all pros, I am sure you will.
  • Up next is the V-Ray tab. I am setting my sampler type to Adaptive, as I find that this usually renders more efficiently. Under colour mapping I am going to raise the multiplier from 1.0 to 2.0. as I decided earlier. I think my scene is still slightly dark so I am raising the overall exposure of my scene here. Again, a good result. I still have my shadows but everything is just that tad lighter. I now need to be careful so I don’t lose the nuances in the shadows.
  • In the Global Illumination tab, I am switching my render engine for the primary bounces to Irradiance Map. Why? Brute Force does give a good overall result, but is in general slower with the render. We have now reached the point where we are refining the render: we want less grain and we are now willing to sacrifice some time on it. Let’s have a look at what the render looks like with the multiplier set to 2.0.

(Multiplier 1.0 on the left, Multiplier 2.0 on the right)

We can also have a play with the light bounces. This basically influences how many surfaces the light will hit before it starts to decay. I have, for this analysis, set the bounces to 1.5. So that you can see the difference.

(Multiplier 1.0 on the left, Multiplier 2.0 on the right, Primary Bounces 1.5)

At this point as you can see the shadows are fading out quite a bit, so the light bounces are too much. I do like how the light works around the little hallways. But I am going to tone it down. Unfortunately, I cannot increase the light bounces without losing those darker shadows, so I am going to leave the light bounces where they are.

So these are the global renders settings I am going to stick wit: sampler type to Adaptive,  raise the multiplier from 1.0 to 2.0, set render engine to Irradiance map, and primary bounces to 1.5.

After a bit of tinkering with some of the lights (my ambient could go down quite a bit as I have raised the multiplier in the global settings) and toning down some of the other lights I am going to go for my final render.

The biggest difference for me between Arnold and V-Ray has to be the render time. Although throughout the process it is rather a bit slower. I did not even consider sending the render to the cloud. My final render time with V-Ray is 7 minutes. That is 90 minutes less than I had with Arnold.


The difference between grain is near to non-existent, but the lights do work differently. There is a lot more yellow light in Arnold, where in V-Ray they stay a bit brighter. All and all, both renders would work for me but it is a bit shocking that the render time is so different, and I’m not the only one who thinks so.

What do you think of the way that we lit and rendered this still? Do you find V-Ray easy to use? Never tried it out before and now desperate to try it out for yourself? Make sure you read our results to see which render engine is best for you!



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